Membrane electrode and blade coating preparation method and application thereof

Abstract

The invention belongs to the field of water electrolysis hydrogen production, and particularly relates to a membrane electrode and a blade coating preparation method and application thereof. The blade coating preparation method provided by the invention comprises the following steps: a) pressing a blade coating substrate to a certain thickness to obtain a pressed substrate; in the step a), the blade coating substrate is nickel foam, nickel felt or carbon paper; b) blade-coating the surface of the pressed substrate with catalyst slurry by using a blade coating machine, drying and hot-pressing to obtain a membrane electrode; in the step b), the ratio of the total mass of the catalyst powder and the binder in the catalyst slurry to the mass of the solvent is 1: (2-4); the distance between a scraper of the blade coater and the pressed substrate is 10-200 [mu] m; the blade coating speed ranges from 1 mm / s to 30 mm / s; the drying temperature is 50 to 90 DEG C. The membrane electrode is prepared by adopting a blade coating process under specific conditions, and the method has the advantages of good coating uniformity of the catalyst layer, high production efficiency and the like, and is particularly suitable for large-scale production of large-area membrane electrodes.

Description

Technical Field

[0001] The present invention belongs to the field of hydrogen production by electrolyzing water, and particularly relates to a membrane electrode, a doctor blade coating preparation method thereof, and an application thereof. Background Art

[0002] The hydrogen production technology of anion exchange membrane electrolyzed water (AEMWE) combines the advantages of using low-cost non-precious metal catalysts in alkaline electrolyzed water (AWE) hydrogen production and the advantages of proton exchange membrane electrolyzed water (PEMWE) hydrogen production technology, such as being directly coupled with renewable energy, fast response speed, high current density, and compact stack design. It is more competitive in industrial applications and has become a key technology for realizing efficient and large-scale green hydrogen production.

[0003] The membrane electrode is a key component in AEMWE hydrogen production. The mainstream preparation method is ultrasonic spraying, that is, the catalyst slurry is coated on the substrate by ultrasonic spraying and then dried to obtain the membrane electrode. Although this method has certain advantages in small-area and high-precision laboratory preparation, there are problems such as poor coating uniformity and obvious edge effects in large-area coating, and the production efficiency is low, making it difficult to meet the requirements of large-scale production. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a membrane electrode, a doctor blade coating preparation method thereof, and an application thereof. The present invention uses a doctor blade coating process under specific conditions to prepare the membrane electrode, which has the advantages of good coating uniformity of the catalytic layer and high production efficiency, and is particularly suitable for large-scale production of large-area membrane electrodes.

[0005] The present invention provides a doctor blade coating preparation method of a membrane electrode, comprising the following steps:

[0006] a) Pressing the doctor blade substrate to a certain thickness to obtain a pressed substrate;

[0007] In step a), the doctor blade substrate is nickel foam, nickel felt or carbon paper; the thickness of the doctor blade substrate is 4 - 6 mm; the thickness of the pressed substrate is 0.1 - 1 mm;

[0008] b) Using a doctor blade coater to scrape the catalyst slurry onto the surface of the pressed substrate, drying, and hot pressing to obtain the membrane electrode;

[0009] In step b), the components of the catalyst slurry include catalyst powder, binder, and solvent, and the ratio of the total mass of the catalyst powder and the binder to the mass of the solvent is 1:(2 - 4); the distance between the doctor blade of the doctor blade coater and the pressed substrate is 10 - 200 μm; the scraping speed is 1 - 30 mm / s; the drying temperature is 50 - 90 °C.

[0010] Preferably, in step a), the pore density of the doctor blade substrate is 75 - 95 ppi.

[0011] Preferably, in step a), the cross-sectional area of the doctor blade substrate in the direction perpendicular to the thickness direction is 200 to 1000 cm 2 .

[0012] Preferably, in step b), the catalyst powder is a nickel-iron-based catalyst powder.

[0013] Preferably, in step b), the binder is one or more of ionomer, polytetrafluoroethylene, polyvinylidene fluoride, polysulfone, and perfluorosulfonic acid-based polymer.

[0014] Preferably, in step b), the mass ratio of the catalyst powder to the binder is (3 to 6):1.

[0015] Preferably, in step b), the solvent is one or more of water, alcohol, dimethyl sulfoxide, N-methylpyrrolidone, and N,N-dimethylformamide.

[0016] Preferably, in step b), the temperature of the hot pressing is 100 to 140 °C, the pressure is 50 to 100 kPa, and the time is 5 to 60 min.

[0017] The present invention provides a membrane electrode, which is prepared by the doctor blade preparation method described in the above technical solution.

[0018] The present invention provides an application of the membrane electrode described in the above technical solution in hydrogen production by anion exchange membrane electrolysis of water.

[0019] Compared with the prior art, the present invention provides a membrane electrode and a doctor blade coating preparation method and application thereof. The doctor blade coating preparation method provided by the present invention comprises the following steps: a) pressing a doctor blade coating substrate to a certain thickness to obtain a pressed substrate; in step a), the doctor blade coating substrate is nickel foam, nickel felt or carbon paper; the thickness of the doctor blade coating substrate is 4-6 mm; the thickness of the pressed substrate is 0.1-1 mm; b) using a doctor blade coater to doctor blade coat a catalyst slurry on the surface of the pressed substrate, drying, and hot pressing to obtain a membrane electrode; in step b), the components of the catalyst slurry include catalyst powder, binder and solvent, and the ratio of the total mass of the catalyst powder and the binder to the mass of the solvent is 1: (2-4); the distance between the doctor blade of the doctor blade coater and the pressed substrate is 10-200 μm; the doctor blade coating speed is 1-30 mm / s; the drying temperature is 50-90 °C. Compared with the traditional ultrasonic spraying method, the present invention significantly improves the preparation efficiency and quality of the membrane electrode by systematically optimizing the doctor blade coating process conditions and the catalyst slurry formulation. Specifically, the present invention first selects a suitable doctor blade coating substrate and pretreatment conditions to ensure the surface flatness and chemical stability of the substrate, providing a basis for uniform coating; secondly, optimizing the solid-liquid ratio of the catalyst slurry, thereby improving the dispersibility and rheological properties of the slurry, so that the catalyst can form a continuous film on the substrate; at the same time, selecting a suitable doctor blade gap and coating speed to ensure the uniformity and consistency of the catalyst coating on the substrate, and preventing the catalyst coating from cracking or peeling by selecting a suitable drying temperature. In addition, in the preferred technical solution of the present invention, the ratio of the catalyst to the binder and the hot pressing process parameters are further optimized, further enhancing the electrochemical performance and mechanical stability of the catalyst coating. Compared with the traditional ultrasonic spraying method, the present invention not only effectively overcomes the defects of poor uniformity and obvious edge effect in large-area coating, but also significantly reduces the equipment cost and process complexity, realizes the efficient and uniform preparation of large-area membrane electrodes, and provides a reliable technical support for the large-scale application of clean energy technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings according to the provided drawings without creative efforts.

[0021] Figure 1 is a physical diagram of the membrane electrode provided in Embodiment 1 of the present invention;

[0022] Figure 2 is a physical diagram of the membrane electrode provided in Embodiment 2 of the present invention;

[0023] Figure 3It is a physical diagram of the membrane electrode provided in Embodiment 3 of the present invention;

[0024] Figure 4 It is a polarization curve graph of the membrane electrodes of Comparative Example 1 and Embodiment 1 provided in Embodiment 4 of the present invention;

[0025] Figure 5 It is a polarization curve graph of the membrane electrodes of Embodiment 2 and Embodiment 3 provided in Embodiment 4 of the present invention. Detailed implementation manners

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] The present invention provides a doctor blade coating preparation method for a membrane electrode, including the following steps:

[0028] a) Press the doctor blade coating substrate to a certain thickness to obtain a pressed substrate;

[0029] b) Use a doctor blade coater to doctor blade coat the catalyst slurry onto the surface of the pressed substrate, dry it, and hot press it to obtain a membrane electrode.

[0030] In the doctor blade coating preparation method provided by the present invention, in step a), the doctor blade coating substrate is nickel foam, nickel felt or carbon paper; the thickness of the doctor blade coating substrate is 4 - 6 mm, specifically 4 mm, 4.5 mm, 5 mm, 5.5 mm or 6 mm; the pore density of the doctor blade coating substrate is preferably 75 - 95 ppi, specifically 75 ppi, 80 ppi, 85 ppi, 90 ppi or 95 ppi; the cross-sectional area of the doctor blade coating substrate perpendicular to the thickness direction is preferably 200 - 1000 cm 2 , specifically 200 cm 2 , 400 cm 2 , 600 cm 2 , 800 cm 2 or 1000 cm 2 .

[0031] In the doctor blade coating preparation method provided by the present invention, in step a), the thickness of the pressed substrate is 0.1 - 1 mm, specifically 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm or 1 mm.

[0032] In the doctor blade coating preparation method provided by the present invention, in step b), the catalyst slurry comprises a catalyst powder, a binder and a solvent; wherein, the catalyst powder is preferably a nickel-iron-based catalyst powder, and more preferably an amorphous nickel-iron-based nanosheet material powder; the binder is preferably one or more of an ionomer, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polysulfone and perfluorosulfonic acid-based polymer (Nafion); the solvent is preferably one or more of water, alcohol, dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP) and N,N-dimethylformamide (DMF); the mass ratio of the catalyst powder to the binder is preferably (3-6):1, specifically 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1 or 6:1; the ratio of the total mass of the catalyst powder and the binder to the mass of the solvent is 1:(2-4), specifically 1:2, 1:2.3, 1:2.5, 1:2.56, 1:2.7, 1:3, 1:3.2, 1:3.5, 1:3.7 or 1:4.

[0033] In the doctor blade coating preparation method provided by the present invention, in step b), the distance between the doctor blade of the doctor blade coater and the pressed substrate is 10-200 μm, specifically 10 μm, 30 μm, 50 μm, 70 μm, 100 μm, 120 μm, 150 μm, 170 μm or 200 μm; the coating speed is 1-30 mm / s, specifically 1 mm / s, 5 mm / s, 10 mm / s, 15 mm / s, 20 mm / s, 25 mm / s or 30 mm / s.

[0034] In the doctor blade coating preparation method provided by the present invention, in step b), the drying temperature is 50-90 °C, specifically 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C or 90 °C; the drying time is preferably 10-120 min, specifically 10 min, 20 min, 40 min, 60 min, 80 min, 100 min or 120 min.

[0035] In the doctor blade coating preparation method provided by the present invention, in step b), the hot pressing temperature is preferably 100-140 °C, specifically 100 °C, 105 °C, 110 °C, 115 °C, 120 °C, 125 °C, 130 °C, 135 °C or 140 °C; the hot pressing pressure is preferably 50-100 kPa, specifically 50 kPa, 55 kPa, 60 kPa, 65 kPa, 70 kPa, 75 kPa, 80 kPa, 85 kPa, 90 kPa, 95 kPa or 100 kPa; the hot pressing time is preferably 5-60 min, specifically 5 min, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min.

[0036] The present invention also provides a membrane electrode, which is prepared by the doctor blade coating method described in the above technical solution.

[0037] The present invention also provides an application of the membrane electrode described in the above technical solution in the electrolysis of water to produce hydrogen using an anion exchange membrane. More specifically, the membrane electrode is used as the anode in the electrolysis of water to produce hydrogen using an anion exchange membrane.

[0038] The technical solution provided by the present invention uses a doctor blade coating process under specific conditions to prepare a membrane electrode, which has the advantages of good coating uniformity of the catalytic layer and high production efficiency, and is particularly suitable for the large-scale production of large-area membrane electrodes. More specifically, the technical solution of the present invention has at least the following advantages:

[0039] (1) Selecting a suitable doctor blade coating substrate and pretreatment conditions to ensure the surface flatness and chemical stability of the substrate, providing a basis for the uniform coating of the catalytic layer.

[0040] (2) Optimizing the solid-liquid ratio of the catalyst slurry, improving the dispersion and rheological properties of the slurry, so that the catalyst can form a continuous film on the substrate; at the same time, selecting a suitable doctor blade gap and coating speed to ensure the uniformity and consistency of the catalyst coating on the substrate.

[0041] (3) Selecting a suitable drying temperature to prevent cracking or peeling of the catalyst coating.

[0042] (4) Optimizing the ratio of the catalyst to the binder and the hot pressing process parameters to further enhance the electrochemical performance and mechanical stability of the catalyst coating.

[0043] (5) Solving the problems of poor uniformity and obvious edge effect existing in the traditional ultrasonic spraying method during large-area coating.

[0044] (6) Greatly improving the production efficiency of the membrane electrode, reducing the equipment cost and process complexity, and solving the defects of low production efficiency and difficulty in meeting the large-scale demand of the traditional ultrasonic spraying method.

[0045] For the sake of clarity, the following will be described in detail through the following examples and comparative examples.

[0046] In the following examples and comparative examples of the present invention, the used NiFe powder catalyst is an amorphous nickel-iron-based nanosheet material, which is prepared by the following method:

[0047] Dissolve 10 mmol nickel dichloride hexahydrate and 5 mmol iron trichloride hexahydrate in 100 mL of deionized water, and stir evenly to obtain a yellow-green solution A; weigh 500 mg of sodium dodecyl sulfate (SDS), add it to 50 mL of deionized water, stir evenly and then add it to solution A. Use 1 M hydrochloric acid to control the pH value to 4 to obtain solution B; under ice bath conditions, dissolve 75 mmol of sodium thioborohydride in 750 mL of methanol to obtain a reducing agent solution C; slowly drip solution C into solution B under the ice bath condition at 10 °C and react for 15 min; then wash, centrifuge, dry and grind the obtained product to obtain an amorphous nickel-iron-based nanosheet material.

[0048] Comparative Example 1

[0049] Prepare a large-size (20×30 cm 2 ) membrane electrode by ultrasonic spraying process, specifically as follows:

[0050] (1) Pretreatment of the spraying substrate:

[0051] Press nickel foam with a thickness of 5 mm, a pore density of 95 ppi, and an area of 20 cm × 30 cm into a nickel foam substrate with a thickness of 0.2 mm, and fix it on the heating plate of the ultrasonic spraying instrument.

[0052] (2) Preparation of the spraying slurry and the membrane electrode:

[0053] Weigh 6 g of NiFe powder catalyst and disperse it in a mixed solvent of methanol and deionized water (200 mL of deionized water and 600 mL of methanol). Then add 2 g of PTFE binder, and after ultrasonic dispersion for 1 h, prepare a catalyst slurry with a mass concentration of 7.5 mg / mL. Use the ultrasonic spraying instrument to spray the catalyst slurry on the nickel foam substrate (spraying speed is 0.11 mL / time, and each time takes 14 s). Place the obtained large-area NiFe-based membrane electrode under a hot press and hot press it at a temperature of 120 °C and a pressure of 100 kPa for 30 min. When the catalyst loading in the membrane electrode is 3 mg / cm 2 , according to the formula calculation, the spraying area for a membrane electrode of 600 cm 2 is not less than 8 hours, and the calculation formula is as follows:

[0054]

[0055] Example 1

[0056] Prepare a large-size (20×30 cm 2 ) membrane electrode by doctor blade coating process, specifically as follows:

[0057] (1) Pretreatment of the doctor blade coating substrate:

[0058] The nickel foam with a thickness of 5 mm, a pore density of 95 ppi, and an area of 20 cm × 30 cm was pressed into a nickel foam substrate with a thickness of 0.2 mm.

[0059] (2) Preparation of the doctor-blade coating slurry and the membrane electrode:

[0060] The nickel foam substrate with a thickness of 1.2 mm was fixed on an automatic doctor-blade coater to ensure its surface was clean and flat. Weighed 2.5 g of solid ionomer and placed it in a 50 mL beaker, then added 32 g of N-methylpyrrolidone and stirred until completely dissolved. Then, weighed 10 g of NiFe powder catalyst and added it to the above mixed solvent, and stirred well to make the catalyst slurry. The catalyst slurry was poured onto the top of the fixed nickel foam substrate, the distance between the doctor blade and the substrate was adjusted to 100 μm, and the running speed of the automatic doctor-blade coater was set to 20 mm / s. After doctor-blade coating, the nickel foam coated with the catalyst was taken off the automatic coating machine and dried in an oven at 70 °C for 1 h. After taking it out, the large-area NiFe-based membrane electrode was placed under a hot press and hot-pressed at 120 °C and 100 kPa for 30 min.

[0061] In this example, the solid ionomer used was obtained by the following method: Weighed 9,9-bis(6-bromohexyl)-9H-fluorene (4.92 g, 10 mmol) and 1,1,1-trifluoroacetone (1.35 g, 12 mmol), added them to a round-bottom flask, added 15 mL of dichloromethane, added 20 mL of trifluoromethanesulfonic acid at 0 °C, reacted for half an hour, the product was precipitated in ethanol, the solid was collected and dried to obtain the crude product, and the crude product was redissolved in chloroform and then reprecipitated in methanol to obtain the initial polymer; weighed the initial polymer (5.86 g, 10 mmol), 5-(4-aminophenyl)-10,15,20-tris(phenyl)porphyrin (0.694 g, 1.1 mmol) and potassium carbonate (0.453 g, 3.3 mmol), dissolved them in 100 mL of N,N-dimethylformamide, heated to 80 °C, reacted under a nitrogen atmosphere for 48 h, and then the reaction solution was cooled to room temperature; added 5 mL of trimethylamine for quaternization and continued to react for 24 h, the product was precipitated in diethyl ether, the solid was collected and dried to obtain the ionomer.

[0062] The physical photograph of the membrane electrode prepared in this example is as Figure 1 shown. It can be seen through Figure 1 that the catalyst formed a continuous coating with a uniform thickness on the substrate surface.

[0063] In addition, for the substrates with the same coating area of 600 cm 2 , the coating time of Comparative Example 1 was not less than 8 h, while the coating time of this example was only a dozen seconds. Thus, it can be seen that the doctor-blade coating process can greatly improve the production efficiency of the membrane electrode.

[0064] Example 2

[0065] Preparation of large-sized (20×30 cm 2 ) membrane electrode is as follows:

[0066] (1) Pretreatment of the doctor blade coating substrate:

[0067] The nickel foam with a thickness of 5 mm, a pore density of 95 ppi, and an area of 20 cm×30 cm is pressed into a nickel foam substrate with a thickness of 0.2 mm.

[0068] (2) Preparation of the doctor blade coating slurry and the membrane electrode:

[0069] Fix the nickel foam substrate with a thickness of 0.2 mm on an automatic doctor blade coater and ensure its surface is clean and flat. Weigh 10 g of NiFe powder catalyst and place it in a 50 mL beaker. Subsequently, weigh 32 g of N-methylpyrrolidone and add it to the same beaker, and stir until completely dispersed. Then, weigh 2.5 g of Nafion binder and add it to the above dispersion, and continue to stir until evenly dispersed to obtain the catalyst slurry. Pour the catalyst slurry onto the top of the fixed nickel foam substrate, adjust the distance between the doctor blade and the substrate to 100 μm, and set the running speed of the automatic film coater to 10 mm / s. After doctor blade coating, take the nickel foam coated with the catalyst off the automatic film coater and put it into an oven at 70 °C for drying for 1 h. After taking it out, place the obtained large-area NiFe-based membrane electrode under a hot press and hot press it at 120 °C and 100 kPa for 30 min.

[0070] The physical photo of the membrane electrode prepared in this example is as Figure 2 shown. It can be seen through Figure 2 that the catalyst forms a continuous coating with a uniform thickness on the substrate surface.

[0071] Example 3

[0072] Preparation of large-sized (20×30 cm 2 ) membrane electrode is as follows:

[0073] (1) Pretreatment of the doctor blade coating substrate:

[0074] The nickel foam with a thickness of 5 mm, a pore density of 95 ppi, and an area of 20 cm×30 cm is pressed into a nickel foam substrate with a thickness of 0.2 mm.

[0075] (2) Preparation of the doctor blade coating slurry and the membrane electrode:

[0076] Fix the nickel foam substrate with a thickness of 0.2 mm on an automatic doctor blade coater, and ensure that its surface is clean and flat. Weigh 10 g of NiFe powder catalyst and place it in a 50 mL beaker. Subsequently, weigh 32 g of N-methylpyrrolidone and add it to the same beaker, and stir until it is completely dispersed. Then, weigh 2.5 g of PTFE binder and add it to the above dispersion, and continue to stir until it is evenly dispersed to obtain a catalyst slurry. Pour the catalyst slurry onto the top of the fixed nickel foam substrate, adjust the distance between the doctor blade and the substrate to 100 μm, and set the running speed of the automatic film coater to 10 mm / s. After scraping, remove the nickel foam coated with the catalyst from the automatic film coater and place it in an oven at 70 °C for drying for 1 h. After taking it out, place the obtained large-area NiFe-based membrane electrode under a hot press and hot press it at 120 °C and 100 kPa for 30 min.

[0077] The physical photo of the membrane electrode prepared in this example is as Figure 3 shown. Through Figure 3 it can be seen that the catalyst forms a continuous coating with a uniform thickness on the surface of the substrate.

[0078] Example 4

[0079] The application effects of different membrane electrodes in anion exchange membrane electrolysis water for hydrogen production are as follows:

[0080] First, use commercial platinum-carbon as the cathode catalyst, configure it into a catalyst slurry, and use an ultrasonic spraying device to spray it evenly on the carbon fiber paper to ensure that the loading amount of the cathode catalyst is 2 mg / cm 2 . Then, select a 50 μm thick commercial anion exchange membrane (Sustainion-X37-50) as the anion exchange membrane. After that, use the membrane electrodes prepared in Examples 1-3 and the membrane electrode prepared in Comparative Example 1 as the anode of the AEMWE respectively. Finally, perform a polarization curve test on the AEMWE electrolysis water device by circulating 1 M KOH solution on the anode side. The test results are as Figures 4 - 5 shown.

[0081] Figure 4 is the polarization curve graph of the membrane electrodes of Comparative Example 1 and Example 1 provided in Example 4 of the present invention. Through Figure 4 it can be seen that at 60 °C, when the membrane electrode prepared in Example 1 is used as the anode of the AEMWE and the current density reaches 2 A / cm 2 , its potential is 1.85 V, which is better than 1.87 V of the membrane electrode prepared in Comparative Example 1.

[0082] Figure 5 is the polarization curve graph of the membrane electrodes of Example 2 and Example 3 provided in Example 4 of the present invention. Through Figure 5It can be seen that under the condition of 60 °C, when the membrane electrodes prepared in Example 2 and Example 3 are used as the anode of the AEMWE and the current density reaches 2 A / cm 2 , the voltages are 1.85 V and 1.81 V respectively, both of which are better than the membrane electrode prepared in Comparative Example 1.

[0083] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a membrane electrode by doctor blade coating, characterized in that, It includes the following steps: a) Press the doctor blade substrate to a certain thickness to obtain the pressed substrate; In step a), the doctor blade substrate is nickel foam, nickel felt or carbon paper; the thickness of the doctor blade substrate is 4 - 6 mm; the thickness of the pressed substrate is 0.1 - 1 mm; b) Use a doctor blade coater to scrape the catalyst slurry onto the surface of the pressed substrate, dry it, and hot press it to obtain a membrane electrode; In step b), the components of the catalyst slurry include catalyst powder, binder and solvent, and the ratio of the total mass of the catalyst powder and the binder to the mass of the solvent is 1:(2 - 4); the distance between the doctor blade of the doctor blade coater and the pressed substrate is 10 - 200 μm; the scraping speed is 1 - 30 mm / s; the drying temperature is 50 - 90 °C.

2. The scraping preparation method according to claim 1, characterized in that, In step a), the pore density of the doctor blade substrate is 75 - 95 ppi.

3. The scraping preparation method according to claim 1, characterized in that, In step a), the sectional area of the doctor blade substrate in a direction perpendicular to the thickness direction is 200 to 1000 cm 2 .

4. The scraping preparation method according to claim 1, wherein In step b), the catalyst powder is nickel-iron-based catalyst powder.

5. The scraping preparation method according to claim 1, characterized in that In step b), the binder is one or more of ionomer, polytetrafluoroethylene, polyvinylidene fluoride, polysulfone and perfluorosulfonic acid-based polymer.

6. The scraping preparation method according to claim 1, characterized in that, In step b), the mass ratio of the catalyst powder to the binder is (3 - 6):

1.

7. The scraping preparation method according to claim 1, characterized in that, In step b), the solvent is one or more of water, alcohol, dimethyl sulfoxide, N-methylpyrrolidone and N,N-dimethylformamide.

8. The scraping preparation method according to claim 1, wherein In step b), the hot pressing temperature is 100 - 140 °C, the pressure is 50 - 100 kPa, and the time is 5 - 60 min.

9. A membrane electrode, characterized in that, The membrane electrode is prepared by the doctor blade coating preparation method according to any one of claims 1 - 8.

10. Application of the membrane electrode according to claim 9 in anion exchange membrane electrolysis water for hydrogen production.

Images